Electric-welding apparatus



Nov. 8, 1927. 1,648,177

L. H. HOFFER ELECTRIC WELDING APPARATUS Filed Nov. 5, 1925 swwmtoz [eroq #029 0" 12f 4 l Wm Patented Nov. 8, 1927.

'UNITED STATES PATENT OFFICE. A

LE ROY H. HOFFER, OF BROOKLYN, NEW YORK, ASSIGNOR T THOMAS E. MURRAY, 03' BROOKLYN, NEW YORK.

ELECTRIC-WELDING APPARATUS.

Application filed November 3, 1925. Serial No. 66,466.

My invention aims to provide an improved welding apparatus with convenient and reliable means for controlling the succession of operations.

Fig. 1 isa diagrammatic view of a complete apparatus;

Fig. 2 is an elevation illustrating an article to be welded. v

The machine is designed to clamp one part of the work while a second part is pressed against the first and a current passed across the joint to weld them together. It is particularly designed for the Murray method of butt-welding in which a current of very high amperage or density in proportion to the area of the joint is used for a very brief interval of time while the parts are pressed together; but the principle of the invention is applicable to welding machines of other types. I

Fig. 2 illustrates a rail bond in which a rod, wire or cable 1 has terminals 2 buttwelded to its ends at the points 3. The present' machine is designed for making this and similar welded joints. It is shown designed to make a single joint. It is proposed, however, to provide a duplicate mechanism to perform a similar operation on the opposite end of the work at the same time.

The machine has two clamping electrodes 4-and, 5 between which the work piece 1 is gripped near its end, and a third electrode 6 which receives the other work piece 2 and presses it against the end of the part 1. The electrode 4 is assumed to be stationary; the electrode 5 being movable downward by means of a toggle 7 operated by the movable core 8 of a solenoid 9. The electrode 6 is mounted directly on the movable core 10 of a second solenoid 11. In operation it is desirable to first actuate the clamping electrode 5 'and' then the electrode 6 which presses the parts together. I have provided special means for timing these operations and the operations of the controlling switches.

The alternating current which is used for welding comes through a switch 12; and the direct current which controls the movements of the parts, through a. switch 13. These two switches are normally closed, and the hand switch 14 open.

Direct current passes from terminal 15 -minal 21 connected by a conductor 21 to the switch 14 and, when the latter is closed, to the return conductor 19. The terminal 21 faces aterminal 22 on the movable end of a lever23 pivoted on the rear of the solenoid, the terminal being connected by a conductor 24 to one end of the solenoid 11, the opposite end of which is connected by a conductor 25 to the conductor 16. As soon as the flux in the solenoid 9 has builtup to a predetermined value, the fixed core 26 pulls the lever 23 against the'resistance of an adjustable spring 27 until the circuit is closed at 21, 22, which energizes the presminal 29 by a conductor 30 to the primary coil 31 of a transfor1ner, the secondary 31 of which has one end 32 connected to the electrode 6, and has branches 33 at the opposite end connected to the electrodes 4 and 5. The return conductor 34 of the primary is connected to a terminal 35 mounted on a pivoted arm 36 which carries a core 37 located in a coil 38. The terminal 35 is adapted to be pulled upward when the coil is energized to contact with a terminal 39 which leads by a conductor 40 to the return terminal 41 of the alternating current switch. A current transformer 42 is located in the line 40, and has its terminals leading to a relay 43 which at a predetermined ampere hour closes a switch 44 in the controlling circuit comprising a conductor 45 coming from one of the direct current terminals and a conductor 46 which leads through va. coil 47 and conductor 48 to a fixed switch blade 49. An adjacent switch blade 50 is connected by a conductor .51 to one end of the 'coil 38 which controls the alternating current circuit. A switch blade 52 normally closes the circuit between the terminals 49 and 50 when the main switches are closed. The switch blade is pivoted on a stationary support 53 which is connected by the conductors 54 and 16 to a direct current terminal. The switch blade has an arm carrying a core 55 located in the coil 47; and carries also a core 56 located'in a second coil 57. By means of these two coils the switch blade is thrown to the open and closing positions. The coil 57 is connected by a conductor 58 to one of the direct current terminals and bya con- (luctor 59 to a terminal 60 mounted on an arm 61 carried by the movable core 8 of the solenoid .9.

Springs 62 press the core and the arm 61 outward, to hold the terminal 60 against a fixed terminal 63 connected by a conductor 64 to the opposite end of the direct current circuit.

The coil 38 which controls the contacts in the alternating current circuit leads by a conductor 65 to a terminal 66 adjacent to a terminal 67 which is connected by a conductor 68 with the conductor 24, previously referred to. The terminal 66 is mounted on an arm 69 pivoted on the frame of the solenoid 11 and pulled downward by an adjustable spring 70. The fixed core of the solenoid 11 has a projection 71 which when the flux in the solenoid 11 has reached a predetermined point attracts the lever 69 and closes the circuit through 66.

Starting with the position of the parts illustrated, the switches 12 and 13 are closed, the latter energizing the coil 57 which holds the switch arm 52 in the closing position. The parts to be welded are inserted. The switch 14 is closed, which energizes the clamping solenoid 9. Upon the first movement of the core, the contacts 60 and 63 are separated and the circuit is opened through the coil 57, which controls the welding current as hereinafter described. As soon as the flux in the solenoid 9 has built up to a predetermined point, the contacts 21 and 22 come together, closing the circuit-through the pressure solenoid 11. Thus in very quick succession the clamping electrodesand the pressing electrode are actuated and the work is ready for the welding current. The solenoids continue to be energized and. to exert a pressure on the electrodes.

When the flux in the solenoid 11 reaches a predetermined point (when the pressure on the work has arrivedat the desired point), the contacts 66 and .67- are closed, completing the circuit through the coil 38, closing the contacts 35 and 39, and passing the current through the transformer and through the work to heat the latter.

The duration of the current is controlled through the relay 43. The current trans- ,a. predetermined interval of ampere hours,

the contacts in the relay are closed,'energiz ing the coil 47, which pulls the switch arm 52 to the open position (the ,pull of the coil 57 having been previously removed). As soon as the arm 52 swings to the open position it breaks the circuit through the coil 47 so as to permit subsequent restoration of the switch arm; and at the same time it breaks the circuit through the coil 38, which allows the contact to be broken at 35, 39, interrupting the welding current and allowing the relay 43 to reset itself. The pressure is continued for a short interval after the current is off. The operator then opens the switch 14, and the solenoids 9 and 11 return to their normal position. When the sole: noid 9 returns, the contacts 60 and 63 are brought together, the coil 57 ener ized and the switch arm 52 pulled to the closing position. The machine is now ready for another cycle of operations.

There is thus an automatic cycle. First the clamping means operates. Immediately thereafter the pressing means operates to press the parts together. And as soon as this-position is attained, the welding current is passed and, after a determined in terval, stopped. And the control of the welding circuit is such' that it cannot again be closed until the hand switch 14 is opened; which immediately resets the mechanism so that the cycle is repeated as soon as the hand switch is closed again. lVith a machine of this sort a very rapid operation and high output can be attained with perfect control of the pressure, current and time interval which are necessary to secure the best re sults.

A particular feature of the invention is the use of the leakage or stray flux of a vsolenoid with its lagging behind the main flux as a means for successively establishing electric circuits. The lagging behind of the leakage flux of one solenoid allows that solenoid to have definitely functioned before the next solenoid is energized.

It. is to be understood that as soon as the main flux passing between the movable core 8 and the fixed core 26 of the solenoid 9 has built up to a suflicient amount to clamp the electrode 5, there will then be a suflicient leakage flux surrounding the fixed pole 26, which will. attract the armature 23. And similarly forthe solenoid 11, when the main flux between the stationary and movable,

cores has built up sutficiently to actuate the core 10, there will then be a suflicient leakage flux surrounding the fixed pole, which will attract the armature on the lever 69.

Various modifications may be made by those skilled in the art without departing from the invention'as defined in the following claims.

\Vhat I claim is:

1. An electric welding machine having clamping means for holding the work and pressing means for pressing the parts together during welding, and means for controlling the latter by the former.

2. An electric welding machine having electrically operated clamping means for holding the work, and "pressing means for pressing the parts together during welding, said pressing means being controlled by the leakage flux of the clamping means.

3. An electric Welding machine having a clamping solenoid for holding the work and a pressing solenoid for pressing the parts together during welding, the circuit of the latter being controlled by the leakage flux of the clamping solenoid.

4. An electric welding machine having clamping means for holding the work, pressing means for pressing the parts together during welding, means for controlling the latter by the former and a welding current circuit controlled by the pressing means.

5. An electric welding machine having a clamping solenoid for holding the work, a pressing solenoid for pressing the parts .together during Welding, the circuit of the latter being controlled by the leakage flux of the clamping solenoid, and a welding current circuit which is controlled by the leakage flux of the pressing solenoid.

6. An electric welding machine having clamping means for holding the work, pressing means for pressing the parts together, a welding current circuit, a switch and means controlled thereby for first clamping the parts, then pressing them together, then closing the welding circuit.

7. An electric welding machine having clamping means for holding the work, pressing means for pressing the parts together, a welding current circuit, a switch and means 10. A welding machine having instrumentalities adapted to act in succession on the work, a'first one of said instrumentalities being electrically operated and a second one leing controlled by the leakage flux of the rst.

11. A welding machine having instrumentalities adapted to act in succession on the work, a first one of said instrumentalities being operated and a second one being controlled by the leakage flux in the first and having its operation initiated When such leakage flux reaches a determined value before the completion of the operation ofthe first instrumentality.

12. In the operation of an electrical machine the method of controlling and timing electrical devices therein which consists in establishin the circuit of a second one by means of t 1e leakage flux of a first oneafter commencing the operation of the first one.

13. In the operation of an electrical machine which includes solenoids for actuating the parts thereof, the method which consists in establishing the'circuit of one solenoid by means of the leakage flux of another solenoid after commencing the operation of the latter. a

In witness whereof, I have hereunto signed my name.

LE ROY H. HOFFER. 

